The winnerWho do you think? Fox's Avatar became the first movie since The Dark Knight two summers ago to hold on to No 1 at the North American charts for four consecutive weekends. It did so in convincing fashion, grossing an estimated $48.5m (£30m) to boost its running total to $429m (£266m) and place James Cameron's space opera at No 7 in North America's all-time box-office pantheon.

Avatar is going great guns overseas, too, where a further $143m in ticket sales saw it easily hold on to the international crown for the fourth weekend in a row and raise its score to $906.2m. That places it second behind Titanic in the all-time overseas chart and second in the global hall of fame when you combine the international and North American tallies.

Can it overtake Titanic in North America? It's possible, but it's now looking unlikely. Avatar probably won't finish above Titanic's $600.1m final score because it seriously shifted down gear this weekend, dropping 29%. That's still a relatively low fall, especially in the fourth weekend, but it's a lot more than the 9% drop last weekend, and if we assume it falls by an additional 10-20 percentage points in each successive week it will peter out before it gets to $600m.

At the international box office, it certainly has the pace to overtake the boat story's $1.242bn total, but can it pull in enough to push past Titanic's $1.842bn combined all-time score? To do so it would need to gross a further $400m or so overseas to add to the $100m that is still possible from North America – after all, Fox top brass expect it to overtake The Dark Knight's $533.3m to become the second biggest domestic release. So in conclusion: maybe, but that's not to take anything away from an incredible piece of visual film-making backed by a formidable marketing effort from the studio.

The loserUniversal's latest romcom Leap Year opened in sixth place on $9.2m. It may have sounded like a good idea in the development meetingsseveral years ago, but pairing the undoubtedly talented Amy Adams with Matthew Goode (the jury's still out on his abilities) just didn't work here. I haven't seen the movie but the reviews have been poor overall and I suspect audiences wanted a break from romcoms. After all, 2009 delivered one of the biggest of all time in the shape of The Proposal – what a 12 months Sandra Bullock is having – and more recently, It's Complicated came out and continues to play well for Universal. The marketplace needs room to breathe a little. Similarly, the Weinstein Company/Dimension also fell foul of audience ennui and its romcom Youth in Revolt starring Michael Cera opened in ninth place on $7m. Will someone please give the appealing Cera something new to sink his teeth into before we all get bored of him?

The real storyIn recent years the studios have discovered that January is a big box-office month. Last year got a good leg-up from the likes of Paul Blart: Mall Cop, Marley and Me, Bride Wars, My Bloody Valentine 3D, Underworld: Rise of the Lycans, and Clint Eastwood's Gran Torino, which opened in December 2008 but expanded throughout January 2009. This year we already have Avatar, which promises to play well throughout the month, as well as next week's new releases (see below), followed by the horror movie Legion with Paul Bettany as a machine gun-wielding angel, Harrison Ford and Brendan Fraser in the tear-jerker Extraordinary Measures, and Dwayne Johnson and Julie Andrews in the family movie The Tooth Fairy.

The futureIt's been almost a decade since Albert and Allen Hughes last made a movie – the deeply flawed but mesmerising stygian gloom that was From Hell – so all eyes will be on their return next weekend with the post-apocalyptic adventure The Book of Eli, starring Denzel Washington, Mila Kunis and Gary Oldman; Warner Bros is releasing in North America. Also new is the Jackie Chan action comedy The Spy Next Door from Lionsgate.